Modeling and application of continuous growth restriction factor for elucidating development of as-welded grain size

Abstract To reveal the as-welded grain growth within the weld pool is one of the hot points in weld solidification. An analytic model of continuous growth restriction factor will addresses this issue very well on the base of the analysis of growth restriction factor development along the solidification pathway within the weld pool, where growth restriction factor has been proved of value in analyzing the grain size. This model combines the solidification continuum and interdependence model, where the solidification continuum is the continuity of solute concentration profile when moving forward along the solidification pathway and the interdependence model describes the nucleation as a function of previous grain growth. The validity of the continuous growth restriction factor is assessed using experimental data from gas tungsten arc welded copper and aluminium alloys. The results show that the model can clearly explain the reasons of the length decrease in the planar growth zone near the fusion boundary by adding inoculants and/or increasing torch speed, as well as the development of grain size within the weld pool for a given composition.